Sandhi Puja is a very significant ritual during Navratri Puja. It is performed at the point when Ashtami Tithi ends and Navami Tithi begins. This is believed to be the moment when Devi Chamunda appeared to kill the demons Chanda and Munda.
Sandhi Puja is dominant for two Ghatis or approximately lasts for 48 minutes. It is possible that Sandhi Puja Muhurta occurs at any time of the day and Sandhi Puja should be done during that time only.
You might also refer the complete Shardiya Navratri Calendar and Durga Puja Calendar.
Navratri Day 1: Saturday 17th October 2020
Pratipada
Ghatasthapana
Shailputri Puja
Navratri color of the day – Grey
Navratri Day 2: Sunday 18th October 2020
Dwitiya
Chandra Darshan
Brahmacharini Puja
Navratri color of the day – Orange
Navratri Day 3: Monday 19th October 2020
Tritiya
Sindoor Tritiya
Chandraghanta Puja
Navratri color of the day – White
Navratri Day 4: Tuesday 20th October 2020
haturthi
Kushmanda Puja
Varad Vinayaka Chauth
Upang Lalita Vrat
Navratri color of the day – Red
Navratri Day 5: Wednesday 21st October 2020
Panchami
Skandamata Puja
Saraswati Awahan
Navratri color of the day – Royal Blue
Navratri Day 6: Thursday 22nd October 2020
Shashthi
Katyayani Puja
Saraswati Puja
Navratri color of the day – Yellow
Navratri Day 7: Friday 23rd October 2020
Saptami
Kalaratri Puja
Navratri color of the day – Green
Navratri Day 8: Saturday 24th October 2020
Ashtami
Durga Ashtami
Mahagauri Puja
Sandhi Puja, Maha Navami
Navratri color of the day – Peacock Green
Navratri Day 9: Sunday 25th October 2020
Navami
Ayudha Puja, Navami Homa
Navratri Parana
Vijayadashami
Navratri color of the day – Purple
Navratri Day 10: Monday 26th October 2020
Dashami
Durga Visarjan
Om Gan Ganpate Namoh. Happy Navaratri!